TP2Location ---Resolve any telephone number to its geographical location.

About Company:
International format of a phone number is the format that some one from out side of your country used to call your number or the format that you use to call some one who live in another country.

Basically a phone number is composed of 4-5 parts. For example :

0044(0)20 8745 5555

00 - IDD Prefix
44 - Country Code
(0) - NDD Prefix (National Direct Dialing Prefix) - Used to call from one city to another city within a Country.
20 8745 5555 - Area Code + Subscriber Number

In the international format, the NDD prefix will NOT be used. Only the following portions are used.
IDD Prefix + Country Code + (Area Code + Subscriber Number)

* The NDD prefix and the IDD Prefix are varies from country to country. Here you can find more dialing rules.

So what happened if i insert a phone number in to TP2Location search box without considering these stuffs ?
Yes, You can insert any phone number without considering these stuffs. But we really need a country code has to be included in the phone number. We format the number you enter using our formula to match our pattern in the database. In case if you did not get the expected result, then you should try enter the number without the NDD Prefix.

More at:http://www.tp2location.com/